Summary In order to understand the principles of long-range connectivity in cortical communication, our efforts have focused on the following two projects. Project 1: Functional connectivity of diverse long-range inputs to the primary somatosensory cortex. To achieve a mechanistic understanding of the functional connectivity of top-down projections to the primary sensory cortex, we have systematically investigated the functional connectivity from the major higher-order cortical areas to the different neuronal types in the primary somatosensory cortex. We found that different higher-order cortical inputs differentially recruit specific subtypes of GABAergic interneurons. Furthermore, this projection specificity to distinct GABAergic neuron subtypes allows the primary somatosensory cortex to parse information from diverse cortical feedback projections. On the basis of this framework, we are investigating how cortical feedback projections to the primary somatosensory cortex are altered in a transgenic mouse line in which one of the neurodevelopmental high-risk genes is mutated. Considering that most neuropsychiatric disorders arise during development, our efforts are focused on the developmental mechanisms of the circuit specificity between cortical areas and within a sensory cortex. Project 2: The structural organization of cortical subnetworks. In the project 2, we aimed to understand the principles that govern the functional heterogeneity of pyramidal neurons in sensory cortex. Neuronal activity in the superficial layer of the primary sensory cortex is highly heterogenous in relation to various aspects of animals behavior. We asked whether functionally heterogeneous subnetworks are constrained by specific long-range and local presynaptic ensembles. This study will provide fundamental insights into the structural organization of the cortical subnetwork of pyramidal neurons that may subserve diverse cortical functions.